Method and vehicle electric system of a motor vehicle with a pre-emptive temporary increase in the idling speed of the internal combustion engine

ABSTRACT

A method is provided for reducing the energy consumption of a motor vehicle having an internal combustion engine and at least one vehicle electric system, to which at least a first electric consumer is connected. In order to achieve an efficient vehicle electric system with a reduced energy consumption, the internal combustion engine is operated in a first operating mode at a first speed. In a second operating mode, the internal combustion engine is operated at a second speed that is higher than the first speed. A driving situation detection device provided in the vehicle recognizes an imminent specific driving situation on the basis of the previous behavior of the driver in controlling the vehicle and/or the behavior of the vehicle in advance, and initiates a switch in the internal combustion engine from the first operating mode to the second operating mode.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of PCT International Application No.PCT/EP2006/011480, filed Nov. 30, 2006, the entire disclosure of whichis herein expressly incorporated by reference.

This application contains subject matter related to the subject matterof application Ser. Nos. 12/474,773 and 12/474,761 entitled “Method andVehicle Electric System of a Motor Vehicle With a Pre-Emptive TemporaryTorque Restriction of the Internal Combustion Engine,” and “Method andVehicle Electric System for a Motor Vehicle With a Pre-Emptive TemporaryLoad Reduction of the Vehicle Electric System,” respectively, filed oneven date herewith.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates, in particular, to a method for reducing theenergy consumption of a motor vehicle having an internal combustionengine and at least one vehicle electric system, to which at least afirst electric consumer (also known as a load) is connected.

The number of electric consumers in motor vehicles has increaseddramatically. In order to reduce the emission of CO2 in the vehicle,hydraulically operating consumers are being replaced increasingly byelectric consumers. Thus, for example, one option is to replace thehydraulic steering of the motor vehicle with an electric power steering(EPS). However, such electric consumers can, in a short period of time,overtax the vehicle electric system with their high power demand. Theresult is that there is also a high demand that the electric system ofthe motor vehicle be stable. In particular, when high loads occur for ashort period of time, adequately high electric voltage or ratherelectric power must be available.

There is therefore needed a method that makes it possible to achieve anefficient vehicle electric system with a reduced energy consumption of amotor vehicle.

This and other needs are met by a method and/or vehicle electric systemfor reducing the energy consumption of a motor vehicle having aninternal combustion engine and at least a first electric consumer orload coupled to the vehicle electric system. The internal combustionengine is operated in a first operating mode at a first speed. In asecond operating mode, the internal combustion engine is operated at asecond speed that is higher than the first speed. A device, which isintended for detecting the driving situation and is provided in thevehicle, recognizes an imminent specific driving situation on the basisof the previous behavior of the driver in controlling the vehicle and/orthe behavior of the vehicle in advance, and initiates a switch in theinternal combustion engine from the first operating mode to the secondoperating mode. Advantageous embodiments of the invention are describedherein.

One aspect of the invention consists of the fact that the internalcombustion engine is operated in a first operating mode at a firstspeed. For example, both the electric generator of the vehicle and thebattery of the vehicle feed jointly the vehicle electric system in orderto supply the electric consumers with an adequate electric voltage. Inthe first operating mode the generator can be loaded to full capacity.

In a second operating mode, the internal combustion engine is operatedat a second speed that is higher than the first speed.

A device, which is intended for detecting the driving situation and isprovided in the vehicle, recognizes an imminent specific drivingsituation on the basis of the previous behavior of the driver incontrolling the vehicle and/or the behavior of the vehicle in advanceand initiates a switch in the internal combustion engine from the firstoperating mode to the second operating mode. Therefore, the inventionprovides that the recognition of an imminent specific driving situationproduces an increase in the speed of the internal combustion engine thatserves to stabilize the voltage of the vehicle electric system when thisvoltage is actually required on short notice. An inventive increase inthe speed can be practical especially in the idling range of theinternal combustion engine between, for example, approximately 500 and1,400 revolutions per minute. A permanently higher speed or the idlingspeed of the internal combustion engine that has a negative impact onconsumption and is intended to compensate for a sudden additional loadon the vehicle electric system can be avoided by means of the solutionof the invention.

One embodiment of the invention provides that on operating the internalcombustion engine in the second operating mode, the device for detectingthe driving situation compares the speed of the internal combustionengine with a predetermined desired speed and on undershooting thedesired speed initiates an increase in the speed of the internalcombustion engine to at least the desired speed. These inventivemeasures can counter a varying load on the vehicle electric system, andthe working range of the electric generator can be returned to a rangehaving a better efficiency level.

One embodiment of the invention provides that the device for detectingthe driving situation takes into consideration who the current driver isand what his previous behavior was. In this way, the hit rate forpredicting that a cornering action is imminent can be raised. If, forexample, the device for detecting the driving situation recognizes thatthe driver in question always swerves during a cornering action (amaneuver that is not always done by every driver), this criterion can beweighted higher in the algorithm for recognizing a cornering action.

One embodiment of the invention provides that the first electricconsumer is an electrically operated steering system of the motorvehicle and the imminent specific driving situation is a corneringaction. Especially during a cornering action it is important for thedriver that the behavior of the steering system be not adversely changedor that the steering not become stiff. During a cornering action thepower requirement of an electric steering system is especially high.

One embodiment of the invention provides that the position of theaccelerator pedal (also referred to herein as a driving pedal or gaspedal) is detected by the device for detecting the driving situation,and the operating mode of the internal combustion engine is switchedfrom the first operating mode to the second operating mode, when thepedal is located largely in its rest position, and at least oneadditional driving situation occurs. Even this feature is acharacteristic of an imminent cornering action and yields an importantindicator of an imminent cornering action.

A further development of the invention provides that the accelerationand the speed of the vehicle are detected by the device for detectingthe driving situation, and the operating mode of the internal combustionengine is switched from the first operating mode to the second operatingmode, when the acceleration of the vehicle is negative, the speed fallsbelow a predetermined threshold value, and at least one additionaldriving situation occurs. This feature, too, is characteristic of animminent cornering action and furnishes an important indicator of animminent cornering action.

A preferred embodiment of the invention provides that the device fordetecting the driving situation checks whether the vehicle is making aswerving maneuver. Driving in swerving mode can give a very clear signof an imminent cornering action.

In one embodiment of the invention, the steering angle of the electricsteering system of the vehicle is detected by the device for detectingthe driving situation. The operating mode of the internal combustionengine is switched from the first operating mode to the second operatingmode, when the absolute value of the steering angle is greater than thepredetermined threshold value, and at least one additional drivingsituation occurs. This feature may be an indicator that the driver isbeginning to make a swerving maneuver or rather a cornering maneuver.

An additional embodiment of the invention provides that the steeringangle of the electric steering system of the vehicle is detected by thedevice for detecting the driving situation, and the operating mode ofthe internal combustion engine is switched from the first operating modeto the second operating mode, when the absolute value of the steeringangle is greater than a predetermined speed-dependent steering thresholdor rather steering angle threshold, and at least one additional drivingsituation occurs. If the driver does not swerve prior to a corneringaction, this characteristic of an imminent cornering action may replacethe “swerving criterion” and may raise the reliability of the predictionof an imminent cornering action.

A further development of the invention provides that the device fordetecting the driving situation checks whether the brake pressure ishigher than a predetermined brake pressure or rather a tolerancepressure and, in addition, checks whether the speed is less than apredetermined acceleration-dependent speed value and/or a dynamiccornering threshold. In this way the reliability of the prediction of acornering action can be increased even more.

In addition, the invention proposes a vehicle electric system of a motorvehicle that exhibits a program-controlled device, which is intended fordetecting the driving situation and carries out the method of theinvention. Furthermore, the invention proposes a program-controlleddevice, which is intended for detecting the driving situation and whichcarries out the method of the invention or initiates its execution.

The inventive method is described in detail below with reference to theflow charts using a cornering action as an example. Identical referencenumerals and symbols show the same functions or functions that have thesame effect.

Other objects, advantages and novel features of the present inventionwill become apparent from the following detailed description of one ormore preferred embodiments when considered in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow chart depicting the main function 1 (the first part) ofan embodiment of the inventive method;

FIGS. 2 and 2 a are a flow chart depicting the main function 2 (thesecond part) of an embodiment of the inventive method;

FIG. 3 is a flow chart depicting the main function 3 (the third part) ofan embodiment of the inventive method;

FIG. 4 is a flow chart depicting the subfunction “steering threshold” ofan embodiment of the inventive method; and

FIG. 5 is a flow chart depicting the subfunction “dynamic corneringthreshold” of an embodiment of the inventive method.

DETAILED DESCRIPTION OF THE DRAWINGS

The starting point for the following embodiment of the inventive methodis the following. The motor vehicle is equipped with an electricsteering system. The electric steering system requires an adequatelyhigh electric voltage for executing a cornering maneuver or rather acornering action. Under some circumstances this voltage cannot beprovided even by the combination of the battery and the electricgenerator of the motor vehicle, both of which are already feedingpower—for example, at largely maximum power output—into the vehicleelectric system. This may be the case especially in the winter, when theelectric seat heater and/or additional consumers or loads with a highelectric connect load are turned on. If a cornering maneuver isinitiated in such a situation without any counter-measures, the voltagein the vehicle electric system collapses significantly due to theadditional load of the electric steering system, because the steeringsystem has to provide a high mechanical torque during a corneringaction, and the steering becomes stiff. This situation is veryunpleasant for the driver, especially during a cornering maneuver thatis to be executed very fast. The inventive method recognizes veryreliably the imminence of a cornering maneuver. The voltage in thevehicle electric system is stabilized by the just temporary increase inthe idling speed, which is advantageous for consumption, from justbefore the cornering maneuver to just after the cornering maneuver.

FIG. 1 shows the first part 100 (main function 1) of an embodiment ofthe inventive method for detecting whether the motor vehicle willperform a cornering maneuver in a short period of time. After beginningin step 101, step 102 compares whether the vehicle is exceeding apredetermined speed x. If no, then the comparison is executed again. Ifyes, then the inventive method for detecting an imminent corneringmaneuver is active, as shown in state 103.

Step 104 compares whether the driving pedal is activated, that is,whether the angle of the pedal is 0 degree (rest position). If no, thenstep 105 checks whether the speed of the vehicle is greater than thepredetermined speed x. If yes, then step 104 is executed again. If no,then the method begins all over again with step 101. If the comparisonin step 104 is positive, the state “foot off the gas” is present, asindicated in state 106.

Step 107 compares whether the acceleration of the vehicle is negative(a<0) and whether the speed is less than or equal to a predeterminedspeed (v<=speed threshold). If no, then the position of the gas pedal isdetected again in step 108. If the driving pedal is not in the reststate, the method begins after step 101. If the driving pedal is notdeflected or rather activated, this state is regarded as the state 106and the comparison 107 is executed again. If the result of thecomparison 107 is “yes,” then the state of the vehicle is “vehicledelayed” (state 109).

The term “curve-corrected steering angle,” which is used below, isdefined as follows. If the vehicle is traveling on a straight road, thesteering angle (the position of the steering wheel) is 0 degree, thatis, straight-ahead driving. If the vehicle is driving in a curve, thenthe steering angle is different from 0 degree. If it concerns, forexample, a uniform left curve, then the steering angle for the timeduration of travel through the uniform left curve is, for example, −10degrees. In order to be able to distinguish this mode of deflecting thesteering wheel (no conscious steering) from an actual steering action(conscious steering action) even in the event of driving through acurve, the method determines the size of the average steering angle fora past short period of time of, for example, 3 seconds, and determinesthe size of the current steering angle. Then, the difference between theaverage steering angle and the current steering angle is formed. Thisdifference is the curve-corrected steering angle.

Step 110 compares whether the absolute value of the curve-correctedsteering angle is greater than a tolerance value, that is, “abs(curve-corrected steering angle)>tolerance value.” A driver will alwaysturn the steering wheel back and forth while driving without anyintention of steering with such motion.

If no, then step 111 checks whether the driving pedal is not deflectedand whether the speed of the vehicle is greater than a predeterminedminimum speed. If yes, then the vehicle is situated in state 109. If no,then the method begins all over again with state 101 “start.” If theresult of step 110 is “yes,” then the current steering angle y in state112 is noted and it is assumed that the first part of a “swerve” couldhave been caused by the driver. The main function 2, shown in FIG. 2, isdescribed in detail below.

FIG. 2 shows the second part 200 (main function 2) of the method. Thesecond part 200 determines in steps 201 to 211 whether the driver has orhas not “swerved,” an action that may be another indicator of animminent cornering action. Many—but not all—drivers swerve before acornering action.

What is meant by the term “swerve” shall be explained, first of all, forthe case of a straight road. If the driver follows the straight courseof the road, the steering wheel stays predominantly in its restposition. In a first mode of a swerving action, the steering wheel ismoved first to the right well beyond the rest position of the steeringwheel and then significantly to the left well beyond the rest position.At the same time the driver moves to the right edge of the driving lanein right traffic, and the front end of the vehicle already pointssomewhat more in the opposite direction than in the straight-aheaddriving mode. In a second mode of a swerving action, the driver movesthe steering wheel first to the left well beyond the rest position ofthe steering wheel and then significantly to the right well beyond therest position.

If the driver swerves, when the vehicle is moving, for example, in aleft-hand curve, then the driving lane moves, so-to-say, under thevehicle to the left—in contrast to a straight road. During a normalcornering action, the steering wheel is turned in conformity with thecurvature of the curve as compared to the 0 position. That is, thesteering angle for a left curve is less than 0 degree and for a rightcurve it is greater than 0 degree.

In order to be able to recognize a swerve even during a corneringaction, step 201 checks whether the steering angle y is greater than 0degree. If no, then the steering angle opposite side=steeringangle+(2*tolerance angle) applies, that is, state 202. If yes, then thesteering angle opposite side=steering angle−(2*tolerance angle) applies,that is, state 203. In both cases the “state=steering recognized” 204applies.

Step 205 re-checks whether the driving pedal is not deflected andwhether the speed is greater than the predetermined minimum speed. Ifno, then the method begins all over again with “start,” that is, withstate 101.

If yes, then step 206 checks whether the current steering angle y isless than the “steering angle opposite side” (cf. state 202 and 203). Ifno, then step 207 checks whether the steering angle opposite side isless than or equal to the current steering angle. If yes, then this isdeemed to be the swerve, as stated in state 211 “swerve recognized.”

If yes, then step 208 checks whether the “steering angle opposite side”is greater than or equal to the current steering angle. If yes, thenthis is deemed to be a swerve, as stated in state 211. If the result ofthe comparison in step 207 or 208 is “No,” then the subfunction“steering threshold” 209 is executed in accordance with the method.

FIG. 4 shows the subfunction “steering threshold” 400 of the method, inwhich a speed-dependent and, thus, dynamic steering threshold is definedfor the additional process steps. Step 401 checks whether the speed ofthe vehicle that is found over a specific period of time is less than 8km/h. The period of time can range, for example, from 3 to 10 seconds.If yes, then the value of the dynamic steering threshold is set at 450degrees (state 402). In the straight-ahead driving mode of the vehicle,that is, for a steering wheel, which is not deflected from thisposition, the angle amounts to 0 degree or 360 degrees. If no, then step403 checks whether the average speed of the vehicle is less than 15km/h, that is, in combination with step 401, whether the average speedlies between 8 km/h and 15 km/h. If yes, then the value of the dynamicsteering threshold is set at 300 degrees (state 404). If no, that is,the speed is greater than 15 km/h, then the value of the dynamicsteering threshold is set at 200 degrees.

Step 210 checks whether the absolute value of the current steering angleis greater than the dynamic steering threshold for the current vehiclespeed. If no, then the method begins all over again with state 204, thatis, “steering recognized.” If yes, then the method continues with themain function 3 in FIG. 3.

If a swerve is considered to be recognized (step 211), then step 212re-checks whether the driving pedal is not activated (angle=0 degree)and whether the speed is greater than the predetermined minimum speed.If no, then the method begins all over again with “start,” that is,after the state 101. If yes, then step 213 checks whether the absolutevalue of the current steering angle is greater than the dynamic steeringangle threshold. If no, then the comparison in step 212 is repeated. Ifyes, then the state “counter-steering recognized” 301 is present and themethod continues with the main function 3, shown in FIG. 3.

In the third part of the method, which is shown in FIG. 3, step 302re-checks at this point whether the driving pedal is not activated andwhether the speed of the vehicle is greater than the predeterminedminimum speed. If no, then the method begins all over again with“start,” that is, after step 101. If yes, then the subfunction “dynamiccornering threshold” 501, shown in FIG. 5, is executed.

In the subfunction “dynamic cornering threshold” 501, shown in FIG. 5,the step 502 checks whether the negative acceleration of the vehiclethat was found during the last seconds ranges from 0 m/s² to −2 m/s². Ifyes, then the value of the dynamic cornering threshold in step 503 isset at 6 km/h. If no, then step 504 checks whether the negativeacceleration ranges from −2 m/s² to −4 m/s². If yes, then the value ofthe dynamic cornering threshold in step 505 is set at the value:absolute value of the acceleration times the factor 3.6. The result is aspeed value. If no, then the value of the dynamic cornering threshold instep 506 is set at 15 km/h.

After step 501, step 303, shown in FIG. 3, checks whether the brakepressure is higher than a predetermined tolerance brake pressure. Inaddition, it is checked whether the current speed of the vehicle v isless than the dynamic cornering threshold, determined in the subfunction“dynamic cornering threshold.” If no, then the method begins all overagain with step 301 in FIG. 3.

If yes, then the “state of imminent cornering recognized” applies instep 304. In step 304, the idling speed of the internal combustionengine is increased from a first idling speed to a second idling speedthat is higher than the first idling speed by means of a correspondinginstruction to the engine control unit of the internal combustionengine. This occurs before the actual cornering maneuver. Then duringthe cornering action an adequately high electric voltage and/or electricpower is available to the electric steering system of the motor vehicle,and a steering stiffness, which would otherwise be present and would beunpleasant for the driver, does not occur owing to the method. After thecornering action has been completed or presumably has been completed,the idling speed is decreased again to the first idling speed that islower than the second idling speed. The termination of the corneringaction can be monitored and recognized, for example, by the device fordetecting the driving situation. One criterion can be, for example, thatthe driver is already driving again straight ahead for a period of timeor that the vehicle has reached a predetermined speed. Similarly, it canbe provided that the cornering action is deemed to be completed after apredetermined time following step 304.

It is clear that the invention can also be carried out in an alternativeembodiment, where the idling speed is already increased at an earliertime in the course of the method. Then, however, the risk of a “falsealarm” may increase. That is, the increase in the idling speed may thenoccur occasionally without any real subsequent need.

The foregoing disclosure has been set forth merely to illustrate theinvention and is not intended to be limiting. Since modifications of thedisclosed embodiments incorporating the spirit and substance of theinvention may occur to persons skilled in the art, the invention shouldbe construed to include everything within the scope of the appendedclaims and equivalents thereof.

1. A method for reducing energy consumption of a motor vehicle having aninternal combustion engine and a vehicle electric system to which atleast a first electric consumer is operatively coupled, the methodcomprising the acts of: providing a first operating mode in which theinternal combustion engine is operated at a first speed; providing asecond operating mode in which the internal combustion engine isoperated at a second speed higher than the first speed; determining animminent specific driving situation, based upon at least one of aprevious driver behavior in controlling the motor vehicle and a behaviorof the motor vehicle in advance, via a driving situation detectiondevice of the vehicle, wherein the driving situation detection devicefactors into consideration an identity of a current driver based on avehicle key being used in the vehicle, and the current driver's previousdriving behavior; and upon determining the imminent specific drivingsituation, initiating a switch from the first operating mode to thesecond operating mode of the internal combustion engine.
 2. The methodaccording to claim 1, further comprising the acts of: comparing by thedriving situation detection device a speed of the internal combustionengine operating in the second operating mode with a predetermineddesired speed; and upon undershooting the predetermined desired speed,initiating an increase in the speed of the internal combustion engine toat least the predetermined desired speed.
 3. The method according toclaim 1, wherein the first electric consumer is an electrically operatedsteering system of the motor vehicle, and the imminent specific drivingsituation is a cornering action.
 4. The method according to claim 1,wherein the first electric consumer is an electrically operated steeringsystem of the motor vehicle, and the imminent specific driving situationis a cornering action.
 5. The method according to claim 1, wherein aposition of a driving pedal is detected by the driving situationdetection device, and the internal combustion engine is switched fromthe first operating mode to the second operating mode, when the drivingpedal is located substantially in a rest position, and at least oneadditional driving situation occurs.
 6. The method according to claim 1,wherein an acceleration and a speed of the motor vehicle are detected bythe driving situation detection device, and the internal combustionengine is switched from the first operating mode to the second operatingmode, when the acceleration of the motor vehicle is negative, the speedfalls below a predetermined threshold value, and at least one additionaldriving situation occurs.
 7. The method according to claim 1, wherein asteering angle of an electric steering system of the motor vehicle isdetected by the driving situation detection device, and the internalcombustion engine is switched from the first operating mode to thesecond operating mode, when an absolute value of the steering angle isgreater than a predetermined threshold value, and at least oneadditional driving situation occurs.
 8. The method according to claim 1,wherein a steering angle of an electric steering system of the motorvehicle is detected by the driving situation detection device, and theinternal combustion engine is switched from the first operating mode tothe second operating mode, when an absolute value of the steering angleis greater than a predetermined speed-dependent steering angle thresholdand at least one additional driving situation occurs.
 9. The methodaccording to claim 1, wherein the driving situation detection devicechecks whether the motor vehicle is making a swerving maneuver.
 10. Themethod according to claim 9, wherein the driving situation detectiondevice checks whether a brake pressure is higher than a predeterminedbrake pressure and, in addition, checks whether a speed is less than atleast one of a predetermined acceleration-dependent speed value and adynamic cornering threshold.
 11. A vehicle electric system of a motorvehicle, comprising a program-controlled device having acomputer-readable medium storing program code segments that: provide afirst operating mode in which a internal combustion engine is operatedat a first speed; provide a second operating mode in which the internalcombustion engine is operated at a second speed higher than the firstspeed; determine an imminent specific driving situation, based upon atleast one of a previous driver behavior in controlling the motor vehicleand a behavior of the motor vehicle in advance, via a driving situationdetection device of the vehicle, wherein the driving situation detectiondevice factors into consideration an identity of a current driver basedon a vehicle key being used in the vehicle, and the current driver'sprevious driving behavior; and upon determining the imminent specificdriving situation, initiate a switch from the first operating mode tothe second operating mode of the internal combustion engine.
 12. Thevehicle electric system of claim 11, wherein the computer-readablemedium further comprises program code segments that: compare a speed ofthe internal combustion engine operating in the second operating modewith a predetermined desired speed; and initiate, upon undershooting thepredetermined desired speed, an increase in the speed of the internalcombustion engine to at least the predetermined desired speed.
 13. Thevehicle electric system of claim 11, wherein a position of a drivingpedal is detected by the driving situation detection device, and theinternal combustion engine is switched from the first operating mode tothe second operating mode, when the driving pedal is locatedsubstantially in a rest position, and at least one additional drivingsituation occurs.
 14. The vehicle electric system of claim 11, whereinan acceleration and a speed of the motor vehicle are detected by thedriving situation detection device, and the internal combustion engineis switched from the first operating mode to the second operating mode,when the acceleration of the motor vehicle is negative, the speed fallsbelow a predetermined threshold value, and at least one additionaldriving situation occurs.
 15. The vehicle electric system of claim 11,wherein a steering angle of an electric steering system of the motorvehicle is detected by the driving situation detection device, and theinternal combustion engine is switched from the first operating mode tothe second operating mode, when an absolute value of the steering angleis greater than a predetermined threshold value, and at least oneadditional driving situation occurs.
 16. A program-controlled device fordetecting a driving situation of a motor vehicle, the program-controlleddevice comprising a computer-readable medium storing program codesegments that: provide a first operating mode in which a internalcombustion engine is operated at a first speed; provide a secondoperating mode in which the internal combustion engine is operated at asecond speed higher than the first speed; determine an imminent specificdriving situation, based upon at least one of a previous driver behaviorin controlling the motor vehicle and a behavior of the motor vehicle inadvance, via a driving situation detection device of the vehicle,wherein the driving situation detection device factors intoconsideration an identity of a current driver based on a vehicle keybeing used in the vehicle, and the current driver's previous drivingbehavior; and upon determining the imminent specific driving situation,initiate a switch from the first operating mode to the second operatingmode of the internal combustion engine.
 17. The program-controlleddevice of claim 16, wherein the computer-readable medium furthercomprises program code segments that: compare a speed of the internalcombustion engine operating in the second operating mode with apredetermined desired speed; and initiate, upon undershooting thepredetermined desired speed, an increase in the speed of the internalcombustion engine to at least the predetermined desired speed.
 18. Theprogram-controlled device of claim 16, wherein a position of a drivingpedal is detected by the driving situation detection device, and theinternal combustion engine is switched from the first operating mode tothe second operating mode, when the driving pedal is locatedsubstantially in a rest position, and at least one additional drivingsituation occurs.
 19. The program-controlled device of claim 16, whereinan acceleration and a speed of the motor vehicle are detected by thedriving situation detection device, and the internal combustion engineis switched from the first operating mode to the second operating mode,when the acceleration of the motor vehicle is negative, the speed fallsbelow a predetermined threshold value, and at least one additionaldriving situation occurs.
 20. The program-controlled device of claim 16,wherein a steering angle of an electric steering system of the motorvehicle is detected by the driving situation detection device, and theinternal combustion engine is switched from the first operating mode tothe second operating mode, when an absolute value of the steering angleis greater than a predetermined threshold value, and at least oneadditional driving situation occurs.